Although there exists extensive information indicating that membrane alterations are involved in the neoplastic process, very little is known concerning the role of phospholipid and sterol alterations in neoplasia. Despite recent advances in understanding of the chemical, physical and molecular properties of lipids in model systems, there is a considerable lack of information correlating these properties with those of normal and neoplastic systems. Almost nothing is known of processes such as phospholipid and sterol exchange that regulate lipid composition in cancer cell membranes, the asymetric distribution of lipids in cancer cell membranes, the regulation of membrane lipid asymmetry, or the possibility of biophysical as well as chemical asymmetry existing in cancer cells. The long-term goals of this proposed research are to provide an in depth study of surface membrane lipid asymmetry in a tumorigenic cell line as follows; 1) The existence of membrane lipid asymmetry in a cell line grown in the absence of serum or hormone supplements will be tested in order to determine if membrane lipid asymmetry can be of de novo origin rather than being imposed on the cell by serum components. 2) The regulation or manipulation of membrane lipid asymmetry will be studied by supplementation of the LM cells with different fatty acids, polar acids, polar head groups, or sterols of both natural origin or synthetic analogues. 3) The possible existence of asymmetric distribution of membrane lipid biophysical properties will be established. 4) The effect of membrane lipid asymmetry alterations on some biological properties of LM cells will be surveyed. The results of these investigations should considerably broaden the scope of knowledge on the role of membrane lipid asymmetry in the neoplastic cell membrane.